Filter discharging mechanism



June 30, 1931. w, GARDELLA 1,812,648

FILTER DI SCH ARGING MECHANI SM Filed Jan. 3. 1929 Patented "June 3.0, 19:31

UNITED STATES-PATENT oFFmE WILLIAM emim naor rtusnme, Lone Ismun, imw You. ASSIGNOR '10 mm UNITED nurses nvconroamnn, or an: rmcrsco, CALIFORNIA, ACORPORATION OF NEVADA rmrna nrscmneme I Application filed iranuary 3, i929. serial'no. 329,971.

' This invention relates in general to filters of the continuous type and while I have illustarted my invention as applied to continuous filters of the drum type, it is obviously applicable to other filters having a screen of either cloth or woven or perforated metal upon whichthe filter cake is deposited during one portionof its revolution and removed during another portion.

It is an object of this. invention to provide a discharger involvin a new method of oper-' ation for removing t e filter cake from the filter medium or screen upon which it has been deposited, which discharger' will be more eflicient in operation, readily renewed or replaced, more durable and which will materially reduce the normal discharger wear on the filter medium.

A further object of this invention 1s to provide a reversely driven discharger roll for removing the filter cake from a continuous fi1-. ter which is spaced away fromthe surface of the filter medium and which wil1-efiectively remove the filter cake without material wear on either the filter medium or the discharge roller. y

It is a further object of this invention to provide a smooth surface roll reversely driven with respect to the surface of acontinuous filter which is adapted to ball up and remove the 'filter cake on the surface of the filter without actually contacting with the filter surface.

. It is astill further object of this invention to disclose a method for removing filter cake from the surface of a continuous ,filt'er comprisinga reversely driven smoothsurfacedischarger roll spaced from thefilter surface.

A further object of the invention is to provide an efficient discharge mechanism for continuous filters which will be of low-original costand have a low upkeep cost.

Further objects and advantages of this in? vention will appear from the following description thereof, taken in conjunction with the attached drawings 'illustrating. preferred forms of embodiment of the invention and in which Figure 1 is an end elevation of a continu-' ous drum filter.

re 2 is a side. elevation of the continu ous fi ter shown in Figure 1.

. over the discharger roll.

In the apparatus heretofore used for disvarious types of adhesion rollers have been used whereby the adhesion of the cake to the roller was greater than the adhesion of the cake to the filter medium. Such a construction is clearly shown in the patent to Genter, No. 1,649,581, and will satisfactorily operate for particularly sticky cakes or slimes but in' a large number of cases the adhesion roller rotating with the filter sufiface does not satisfactorily remove the cake.

re 3 showing the advanced position in charging the filter cake from the filter screen, p I

In some cases, it has been found thatthe relative adhesion to the discharger roll and to the filter surface is so nearly the same that such rolls are not 'eifectiveto bring about a oomplete'and satisfactory discharge of filter pulp. Furthermore, with the continuous fil'-' ter of the drum type, such as is disclosed herein and which is usually wound with a wire in a spiral formation to retain the filter mediumclose to the supporting structure, the

adhesive roller is undesirable and objectionable and causes considerable wear. I

The use of positively driven brushes or other wiping mechanisms are also undesirablebecause of the considerable wear both on the brushes and on the filter medium. Furthermore, the brushes tend to break up the filter cake rather than'discharge the cake in a continuous sheet as the present structure will do."

. I have herein illustrated a continuous filter of the drum type comprising the drum 10 which rotates in the filter tank 12 by the well known operation of (the driving mechanism 14. The surface of the drum 10 is provided with a filtering medium 16' on which a cake is formed during the rotation of the filter drum through the filter tank 12 by the vacuum communicated-to the filter segments through the center shaft and it is essential that this filter cakebe removed completely in each cycle of operation. The great expanse of filter medium 16 usually requires a suitable wire winding 18 for support as is the Well known construction of the drum type of filter shown in the patent to E. L. Oliver, No: 919,628, dated April 27, 1909.

In order to remove the filter cake, which forms during the periodic rotation of the filter drum, I provide a discharger roll 20 supported on the ends by the bearings 22 and 24 and centrally by the bearing 26. This roll is positively driven by a chain or other driv ing means 28 from the central shaft 30 in the same direction as the drum itself is driven which brings about a peripheral rotation opposite to that of the periphery of the drum at the point of nearest approach-as indicated by the arrows in Figures 3 and 4.

The discharger roll 20'is spaced from the filter medium 16 and the wires 18 thereon, as is more particularly shown in Figures 3 and 4*, and does not actually contact with either the filte'r medium or the wire winding. Un der such circumstances, there is no appreciable wear on either the filter medium 16 or the wires 18 or the roller 20 at which point the suction on the filter surface is cut offdue to.

the discharge of the filter cake.

As the filter rotates through its cycle'oi suction, during which eriod the filter cake is built up on the perip cry of the drum and subsequently is dried, the filter cake reaches the position as shown in Figure 3 adjacent the dischargerroll 20. I As the discharger roll is revolving on the periphery opposite the peripheral direction of the drum,- and pref erably at a slightly higher surface speed than the speed of the drum 10. the filter cake is rolled backward into a ball or roll, as shown at '32, until it reaches such a condition that the ball 32a is higher than the discharger roll 20 whereupon it will continue in the direction'of the discharger roll 20 until it will pass over the top of the discharger roll and will then drop by gravity into the position, as

' shown in Figure 4. After the first cake has started and reached theposition as shown in Figure 4;, it will be found that the filter cake will continuously pass over the periphery of i the discharger roll 20 and may be dropped into anysuitable receptacle or conveyed to a desired point. In case of stoppage of the fil ter or if the cakeshould actio ,as shown in Figure 3, will take place again ntil the cake is of such size as to pass over the periphery of the discharger roll.

In practice, it has been found that a smooth surface brass roll, approximately three inches in diameter, is most desirable for a drum" eight feet in diameter on which a filter cake of paper pulp is built u-p.' It is necessary that the discharger roll 20 be located as much below the top of the filter as possible and spaced break, the balling.

clear but. not distant from the surface inasmuch as the tendency (of the filter cake to 4 pass over the periphery of the discharger roll is greatly augmented by the force of gravity. It is obvious that if the discharger roll were placed near the top of the drum, someexternal means would be necessary 1 to force the cake over the discharger roll, Whereas in the position as shown in Figure 1 the cake will tend more readily to follow and pass over the discharger roll.

The operation of this device can easily be distinguished from the operation of the previous devices whichrequired a high coefiicient of'adhesion to force the filter cake to leave the filter medium and follow the contour of the discharge means. In the present case, the roll by rotating in an opposite peripheral direction to the drum will necessarily cause a balling up of the filter cake and when the.

cake reaches such proportions as to pass over the top of the discharger roll, the cake will then be removed in a substantially continuous sheet.- g

The discharger roll 20 is of such small diameter with respect to the length of the drum that a central bearing 26 is usually desirable.

to form a crowned on depressed filter cake in e the center of the drum, the discharger roll 20 will operate equally well. I

The material from which the discharger roll 20 may be made will vary somewhat under the circumstances and under the conditions of operation and will depend also on the nature of the material to be filtered. It

has been found that a smooth brass roll is particularly desirable for discharging paper pulp and felt or rubber covered rolls are par-. ticularly desirable for other materials. It is also obvious that any smooth metal or wood or stone or fabric roll may be used without changing from the broad method of operation or a corrugatediron roll having a rubber cover could be used under certain conditions.

The principal features therefore of my invention are that a reversely rotating dis charger roll, spaced from the filter surface,

is used, that it operates by balling up'the filter cake, forming a ball of such a size that it will pass over the surface of the discharger roll to start the continuous discharge wh1ch will continue aided by gravity, so that the filter cake will finally be discharged in a continuous sheet. The speed of rotation .of the v discharger roll will be the same peripheral speed as the surface of the drum, so that after i the cake is started and is being removed in a continuous sheet, the discharger roll will draw the cake directly from the surface of the drum rather than permitting itto ball up subsequent to the initial start. No blow backis necessary as the'cake will come 01f by the contact with the reversely rota-ting roll. A

5 further feature is that the discharger roll is spaced slightly from and does not come-in contact with the filter medium in itselfand will not cause any wear on the filter medluin;

As the filter drum and the discharger roll are free'to' rotate, the wear on the apparatus is materially reduced. The discharger roll must be of a relatively small diameter being approximately one thirty-second the size-oi the filter drum andwill extend throughout the length of .the alignment. It will also be loca'ted'materially below the topoithe drum so that the I force of gravity" willaid the rollin removing the filter'cake. 1 A While 'I haveshown preferredforms of various other modifications might be made .7 therein and I, therefore, de'sire a broad interspirit -and spirit of the appended claims.

I- claim: 1

' 1.. In combination with a continuous rotating drum filter having a filter medium on the cylindrical surface thereof and to have a filter cakie'built up thereon, a smooth the filter medium, being supported centrally, if necessary, to maintainpretation of the device within the scope and of the disclosure and within the scope ing the filter medium'and without wear on sald filtermedium. a 4. The combination in a-rota'ry continuous filter. having a .woven filter medium of a filter .qcake discharger comprising :a roller spaced u from the .filtering mediumof said filter and not contacting therewith, means to "rotate said rollerso tering medium. J:

that the surface nearest the fil surface moves in adirection opposite to the rotation ofsaidfilter to strip the filter cake from said filten without touching the v filter'medium and wi'thoutwear onisaid filter In testimony whereof I have afiixed my signature to this specification, I

a WILLIAM *GARDELLA.

embodiment of my invention, I am aware that adapted i metal dischargerroll, Said discharger roll I being spaced a slight distance-from the filter said drum and nearer the horizontalaxis medium and being located below the top of p thereof than the vertical axis on the cake dis filter, 'endfbearings supthefsurface nearestthe filter drum movesm the top of the: roll and 2. Thecombination in a rotary drum com a tinuou's filter of a discharge roller, com ris- 'ing a .smoothvmetallic cylinder spaced torotate said roller so thatthesurface nearthe filtering surface of said drum, and means v est the drum; movesin a direction opposite filter surface;

'tinuous filter having a woven'filter, medium 3. The combination in a rotary drum conto the rotation of said drum .to strip the filter cake from said drum without wear on said of a filter cake discharger comprising a cyl- I at; a 

